In recent years, as the technique capable of carrying out high density magnetic recording in a 1 Tbit/inch2 class, attention is paid to a thermally assisted magnetic recording method. The thermally assisted magnetic recording method is a technique for carrying out magnetic recording over a magnetic recording medium having a high holding power which is resistant to a thermal fluctuation. The thermally assisted magnetic recording method has a method of converting a laser beam into a near-field light by a near-field light generating unit and irradiating the near-field light thus obtained by the conversion on a part of a surface of a magnetic recording medium to locally raise a temperature of the magnetic recording medium, thereby applying a magnetic field to a portion in which the temperature is raised, thereby recording information magnetically. At this time, efficiency for converting a laser beam into a near-field light is low. For this reason, most of energy of the laser beam is converted into heat. Therefore, it is desired that the heat of the near-field light generating unit should be radiated efficiently.